This paper presents a review of research carried out in the past 40 years into various aspects of noise in open plan classrooms. The emergence of open plan classroom design in response to progressive educational reforms is discussed. A limited amount of evidence of the effects of noise in open plan classrooms is presented. Surveys of both background and intrusive noise levels in open plan classrooms are summarized and compared. Differences between noise levels in open plan and enclosed classrooms are also considered. Recommended noise limits and acoustic design criteria for open plan classrooms are discussed, together with some current international standards. The paper concludes with a discussion of appropriate noise control measures to reduce noise and maximize speech intelligibility and speech privacy in open plan classrooms.

Effects of noise and reverberation on speech perception and listening comprehension of children and adults in a classroom-like settingMaria Klatte, Thomas Lachmann, Markus MeisOctober-December 2010, 12(49):270-282DOI:10.4103/1463-1741.70506 PMID:20871182

The effects of classroom noise and background speech on speech perception, measured by word-to-picture matching, and listening comprehension, measured by execution of oral instructions, were assessed in first- and third-grade children and adults in a classroom-like setting. For speech perception, in addition to noise, reverberation time (RT) was varied by conducting the experiment in two virtual classrooms with mean RT = 0.47 versus RT = 1.1 s. Children were more impaired than adults by background sounds in both speech perception and listening comprehension. Classroom noise evoked a reliable disruption in children΄s speech perception even under conditions of short reverberation. RT had no effect on speech perception in silence, but evoked a severe increase in the impairments due to background sounds in all age groups. For listening comprehension, impairments due to background sounds were found in the children, stronger for first- than for third-graders, whereas adults were unaffected. Compared to classroom noise, background speech had a smaller effect on speech perception, but a stronger effect on listening comprehension, remaining significant when speech perception was controlled. This indicates that background speech affects higher-order cognitive processes involved in children΄s comprehension. Children΄s ratings of the sound-induced disturbance were low overall and uncorrelated to the actual disruption, indicating that the children did not consciously realize the detrimental effects. The present results confirm earlier findings on the substantial impact of noise and reverberation on children΄s speech perception, and extend these to classroom-like environmental settings and listening demands closely resembling those faced by children at school.

Effects of prior exposure to office noise and music on aspects of working memoryAndrew Smith, Beth Waters, Hywel JonesOctober-December 2010, 12(49):235-243DOI:10.4103/1463-1741.70502 PMID:20871178

Previous research has suggested that prior exposure to noise reduces the effect of subsequent exposure due to habituation. Similarly, a number of studies have shown that exposure to Mozart's music leads to better subsequent spatial reasoning performance. Two studies were conducted to extend these findings. The first one examined whether habituation occurs to office noise (including speech) and, if so, how long it takes to develop. Thirty-six young adults participated in the first study which compared effects of office noise with quiet on the performance of a maths task. The study also examined the effects of prior exposure to the office noise on the subsequent effect of the noise. The results showed that performance was initially impaired by the office noise but that the effects of the noise were removed by 10 minutes of exposure between tasks. The second experiment attempted to replicate the "Mozart effect" which represents an improvement in spatial reasoning following listening to Mozart. The study also examined whether the Mozart effect could be explained by changes in mood. Twenty-four young adults participated in the study. The results replicated the Mozart effect and showed that it was not due to changes in mood. Overall, these results show that prior exposure to noise or music can influence aspects of working memory. Such effects need to be incorporated into models of effects of noise on cognition and attempts have to be made to eliminate alternative explanations rather than just describing changes that occur in specific contexts.

One mental activity that is very vulnerable to auditory distraction is serial recall. This review of the contemporary findings relating to serial recall charts the key determinants of distraction. It is evident that there is one form of distraction that is a joint product of the cognitive characteristics of the task and of the obligatory cognitive processing of the sound. For sequences of sound, distraction appears to be an ineluctable product of similarity-of-process, specifically, the serial order processing of the visually presented items and the serial order coding that is the by-product of the streaming of the sound. However, recently emerging work shows that the distraction from a single sound (one deviating from a prevailing sequence) results in attentional capture and is qualitatively distinct from that of a sequence in being restricted in its action to encoding, not to rehearsal of list members. Capture is also sensitive to the sensory task load, suggesting that it is subject to top-down control and therefore avoidable. These two forms of distraction-conflict of process and attentional capture-may be two consequences of auditory perceptual organization processes that serve to strike the optimal balance between attentional selectivity and distractability.

Previous studies have found that chronic exposure to aircraft noise has a negative effect on children's performance on tests of episodic memory. The present study extended the design of earlier studies in three ways: firstly, by examining the effects of two noise sources, aircraft and road traffic, secondly, by examining exposure-effect relationships, and thirdly, by carrying out parallel field studies in three European countries, allowing cross-country comparisons to be made. A total of 2844 children aged between 8 years 10 months and 12 years 10 months (mean age 10 years 6 months) completed classroom-based tests of cued recall, recognition memory and prospective memory. Questionnaires were also completed by the children and their parents in order to provide information about socioeconomic context. Multilevel modeling analysis revealed aircraft noise to be associated with an impairment of recognition memory in a linear exposure-effect relationship. The analysis also found road traffic noise to be associated with improved performance on cued recall in a linear exposure-effect relationship. No significant association was found between exposure to aircraft noise and cued recall or prospective memory. Likewise, no significant association was found between road traffic noise and recognition or prospective memory. Taken together, these findings indicate that exposure to aircraft noise and road traffic noise can impact on certain aspects of children's episodic memory.

Chronic aircraft noise exposure in children is associated with impairment of reading and long-term memory. Most studies have not differentiated between day or nighttime noise exposure. It has been hypothesized that sleep disturbance might mediate the association of aircraft noise exposure and cognitive impairment in children. This study involves secondary analysis of data from the Munich Study and the UK Road Traffic and Aircraft Noise Exposure and Children's Cognition and Health (RANCH) Study sample to test this. In the Munich study, 330 children were assessed on cognitive measures in three measurement waves a year apart, before and after the switchover of airports. Self-reports of sleep quality were analyzed across airports, aircraft noise exposure and measurement wave to test whether changes in nighttime noise exposure had any effect on reported sleep quality, and whether this showed the same pattern as for changes in cognitive performance. For the UK sample of the RANCH study, night noise contour information was linked to the children's home and related to sleep disturbance and cognitive performance. In the Munich study, analysis of sleep quality questions showed no consistent interactions between airport, noise, and measurement wave, suggesting that poor sleep quality does not mediate the association between noise exposure and cognition. Daytime and nighttime aircraft noise exposure was highly correlated in the RANCH study. Although night noise exposure was significantly associated with impaired reading and recognition memory, once home night noise exposure was centered on daytime school noise exposure, night noise had no additional effect to daytime noise exposure. These analyses took advantage of secondary data available from two studies of aircraft noise and cognition. They were not initially designed to examine sleep disturbance and cognition, and thus, there are methodological limitations which make it less than ideal in giving definitive answers to these questions. In conclusion, results from both studies suggest that night aircraft noise exposure does not appear to add any cognitive performance decrement to the cognitive decrement induced by daytime aircraft noise alone. We suggest that the school should be the main focus of attention for protection of children against the effects of aircraft noise on school performance.

Perceptual load and cognitive load can be separately manipulated and dissociated in their effects on speech understanding in noise. The Ease of Language Understanding model assumes a theoretical position where perceptual task characteristics interact with the individual's implicit capacities to extract the phonological elements of speech. Phonological precision and speed of lexical access are important determinants for listening in adverse conditions. If there are mismatches between the phonological elements perceived and phonological representations in long-term memory, explicit working memory (WM)-related capacities will be continually invoked to reconstruct and infer the contents of the ongoing discourse. Whether this induces a high cognitive load or not will in turn depend on the individual's storage and processing capacities in WM. Data suggest that modulated noise maskers may serve as triggers for speech maskers and therefore induce a WM, explicit mode of processing. Individuals with high WM capacity benefit more than low WM-capacity individuals from fast amplitude compression at low or negative input speech-to-noise ratios. The general conclusion is that there is an overarching interaction between the focal purpose of processing in the primary listening task and the extent to which a secondary, distracting task taps into these processes.

The role of working memory capacity in auditory distraction: A reviewPatrik SörqvistOctober-December 2010, 12(49):217-224DOI:10.4103/1463-1741.70500 PMID:20871176

The purpose of this paper was to review the current knowledge on individual differences in susceptibility to the effects of task-irrelevant sound on cognition. The literature indicates that at least two functionally different cognitive mechanisms underlie those differences; one is the efficiency by which people process the order between perceptually discrete sound events and the other is related to working memory capacity. The first mechanism seems to be involved only when disruption is a function of conflicting order processes, whereas the other mechanism is involved in a wider range of phenomena including those when attentional capture and conflicting semantic processes form the basis of disruption. Because of this, noise abatement interventions should first of all be directed towards people with low working memory capacity. Implications for theories of auditory distraction are discussed.

Mental tasks are susceptible to disruption by concurrent to-be-ignored speech. The goal of the present paper is to examine whether a theoretical framework successfully applied to irrelevant speech effects in serial recall-interference by process-can be extended to verbal tasks in which meaning is the basis of retrieval and to which the irrelevant sound is related to different degrees by meaning. That the semantic characteristics of the to-be-ignored sound interact with the predominance of semantic retrieval in the focal task to determine the degree of disruption is demonstrated in three settings: free recall, category-clustering and fluency. Source monitoring-the difficulty in discriminating episodic information on the basis of the sense modality (visual or auditory) in which it was presented-contributes in part to the disruption by speech. The power of alternative accounts-interference-by-content and attentional capture-to predict these outcomes is also discussed.

Comment on "The state of the art of predicting noise-induced sleep disturbance in field settings"Mathias Basner, Barbara Griefahn, Keneth I HumeOctober-December 2010, 12(49):283-284DOI:10.4103/1463-1741.70508 PMID:20871183